Just 40 years ago, the 1964 Surgeon General’s Report on Smoking and Health alerted the American public to the health risks of cigarette smoking. It launched a remarkably successful public health campaign that dramatically cut adult smoking prevalence, from 42.4% in 1965 to 22.8% in 2001, and recast the cultural acceptability of tobacco use.1 Less well known is the fact that the cigarette itself has undergone major change in the past 40 years. Today’s 46.2 million American smokers buy a product very different from the cigarette sold in 1964.

In the late 1960s, tobacco manufacturers introduced light or low tar brands that yielded 7 14 mg tar per cigarette, compared to the 22 mg tar of the average cigarette sold at that time.2 Later, ultralight brands appeared, with tar yields below 7 mg per cigarette. Today, almost 90% of cigarettes sold in the United States are in these categories.3 Better taste is not the reason why smokers buy light cigarettes. They buy them because they have the misconception that smoking lower tar products reduces their risk of lung cancer and other tobacco related diseases.4 Advertisements for these

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Cannabis use may increase the likelihood of becoming addicted to nicotine, suggests a study in rats funded by the National Institute on Drug Abuse.

Data from previous epidemiologic studies have suggested that people who smoke marijuana are more likely to become addicted to cigarettes, but the reason why was unclear.

To probe whether biological factors may be involved, the researchers injected rats with tetrahydrocannabinol (THC), the main psychoactive component of cannabis, for 3 days (Panlilio LV et al. Neuropsychopharmacology. doi 10.1038/npp.2013.16 published online January 10, 2013 ). A week later the investigators implanted catheters in the animals to give them an intravenous dose of nicotine or a placebo when they completed a task. Of rats in the nicotine group, 94% learned to complete the task to get their dose, compared with 65% of the placebo group. When the rats had to work harder to obtain the dose, those in the nicotine group were more likely to persist.